Load interrupting device



Sept. 6, 1960 Filed Aug. 21, 1958 F. J. SCHULTZ LOAD INTEZRRUPTINGDEVICE 3 Sheets-Sheet 1 INVENTOR.

Fred J Scfiuizfz BY 31 w p 1960 F. J. SCHULTZ 2,951,924

LOAD INTERRUPTING DEVICE Filed Aug. 21, 1958 3 Sheets-Sheet 2 INVENTOR.Fred J Sc/zuZtz m BY K MQ Si 1 Sept. 6, 1960 F. .1. SCHULTZ LOADINTERRUPTING DEVICE 3 Sheets-Sheet 3 Filed Aug. 21, 1958 1 Lian/mm II!!!II INVENTOR. Fred J Sc/wltz Y B M Lj dftcarm y Patented Sept. 6, 1960LOAD INTERRUPTING DEVICE Fred J. Schultz, Milwaukee, Wis., assignor toMcGraw- Edison Company, Milwaukee, Wis., a corporation of Delaware FiledAug. 21, 1958, Ser. No. 756,468

9 Claims. (Cl. 200120) This invention relates in general to loadinterrupting devices and more particularly relates to a loadinterrupting device well adapted for fuse cutouts, switches, and thelike.

In fuse cutouts and the like, auxiliary load devices are often used tobypass current at the point of electrical engagement of the fuse tubewith the fixed terminal contacts of the cutout to prevent arc damagethereat or possible apparatus fiashover when opening the cutout underload. The prior practice in the design of load interrupting devicesrequires relatively large rotational or longitudinal motion to separatethe auxiliary contacts. This is particularly objectionable in housedcutouts because of space limitations. The are interruption of priordevices is generally aided by the generation of gases caused by playingof the arc on fibre pieces or the like. This is objectionable becauseventing of the gases may harm a lineman. Another generally acceptedmethod of interrupting arcs is the so called cam follower method whichrequires a rather large longitudinal motion and generally requiresmounting on the exterior of the housed cutout. Exposure of the parts tothe elements and proximity thereof to the lineman are objectionable.Still another type of prior art load interrupting device attempts toforce gases or oil through the arc path by means of various mechanicaldevices. These devices are complicated and cumbersome.

It is an object of the present invention to provide a load interruptingdevice which requires relatively short contact separation and therebyconserves on space requirements necessary to afford such movement.

It is a further obiect of the invention to provide an arc interrupterwherein the arc is rapidly moved between spaced auxiliary contacts bymagnetic means so that the arc is spun around the periphery of thecontacts to prevent burning of the latter while affording a highinterrupting rating.

A further object of this invention is to provide a-rc inter ruptingmeans of the type aforementioned wherein magnetic means is used to forcethe arc through a fluid arc extinguishing medium thus eliminatingmechanical puffer or plunger devices.

It is a further object of this invention to provide a load interruptingdevice which may be easily sequentially stacked in series to accommodatevarious voltage requirements.

It is a further object of this invention to provide an arc interruptingdevice of the type aforestated which because of compactness isparticularly well adapted to disposal within the confines of a housedfuse cutout.

It is a further object of this invention to provide a load interruptingdevice for a fuse cutout or the like which is simple in construction,has a minimum of parts, is well adapted to the mass manufacturingprocess and is otherwise well adapted electrically and mechanically forthe purposes for which it was designed.

The novel features that are characteristic of this invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and its method of operationtogether with additional objects and advantages thereof will best beunderstood by the following description of a specific embodiment whenread in connection with accompanying drawings in which:

Fig. 1 is a vertical sectional view of a housed fuse cutout embodyingthe concepts of my invention;

Fig. 2 is a sectional view taken along lines 2-2 of Fig. 1;

Fig. 3 is a sectional view similar to Fig. 1 showing the relativeposition of the parts during opening movement of the door to the housedcutout;

Fig. 4 is a sectional view similar to Fig. 2 showing the relativepositional relationship of the parts of the load interrupter when thedoor of the cutout is in the position shown in Fig. 3;

Fig. 5 is a semidiagrammatic view, partially in section, illustratingthe relative position of th interrupting apparatus when the contacts arein engaged relation;

Fig. 6 is another semidiagrammatic view similar to Fig. 5 showing therelative position of the parts and the cooling movement of the are whenthe contacts are in sepa-rated relation; and

Fig. 7 is a semidiagrammatic view similar to Fig. 5 illustrating theelectrical circuitry when a permanent magnet is substituted for theelectromagnetic coil.

While the auxiliary load interrupting device is shown and described witha housed fuse cutout, it is to be noted that it is also well adapted forattachment to any switching device where it is desired to have anauxiliary load break function.

Turning to the drawings, Fig. 1 shows a housed fuse cutout comprisinginsulated housing 10 having a door 11 'rotatably mounted thereon forenclosing the electrical components disposed within said housing.Fixedly mounted within the housing 10 is a first terminal means 12comprising upper contact means 13 and upper electrical conductor means14 which is adapted to be attached to a line connector not shown. Thecontact means 13 is generally U-shaped in configuration to receive andembrace the contact cap 20 of the fuse tube as shall be later explained.

Second terminal means 15 is disposed below the first terminal meanswithin the housing 10 and comprises U- shaped contact fingers 16 and thelower connector means 17 adapted to engage another conductor (notshown). Fuse means 13 is mounted on the door 11 and is adapted todetachably bridgingly engage the first and second terminal means. Thefuse means comprises a fuse tube formed of insulating material having aconducting cap 20 at the upper end thereof for cooperation with contacts13. A contact sleeve 22 is embracingly disposed about the middle of thefuse tube and mounts the latter to the door in addition to engaginglower contact 16. A headed fuse link cable is disposed within the fusetube 19 and is electrically connected to cap 20 at one end and to thecontact sleeve 22 at the other end by means of a mounting clamp 24. Anarticulated spring biased flipout means 23 is attached to the contactsleeve 22 to move the fuse link cable 21 from within the fuse tube uponrupturing of the link. The foregoing subject matter except forconfiguration of the housing 10 and door 11 is standard in the art andrepresents generally conventional prior art practice.

An auxiliary load interrupting device 25 is fixedly disposed within theupper portion of housing It by generally channel shaped mounting means26 which is electrically connected to the upper or first terminal means12 by suitable connector strip 27. As shown the connector strip 27 maybe integral with the upper terminal means or a separate member ifdesired. The auxiliary load interrupting device 25 comprises a generallycylindrical housing means 28 formed of insulating material having anaxially aligned bellows 29 mounted on the right hand side as viewed inFig. l. The bellows 29 is flexible and extensible and is preferably madeof copper or other good conducting material. Dependingly attached to themovable end 30 of the bellows is an auxiliary contact spring 31 which isso formed as to engage the cap 20 on the fuse tube 19. Thus, anauxiliary circuit is formed between the first terminal means 12 and thefuse cap 20 through conducting strip 27, mounting means 26, theinterrupter means 25 and contact spring 31.

The interrupting device 25 per se comprises the mounting and conductingbolt 32 which is fixedly axially disposed in the housing 28 and extendsthrough an aperture 33 formed in the mounting means 26. A nut 34 firmlyafiixes the bolt 32 to the mounting means to afford a good mechanicaland electrical connection to hold the assembly 25 in rigid relation tothe housing 11. Annular coil means 35 formed of'copper windings or thelike is concentrically disposed within the housing 28 and iselectrically connected to bolt 32 by soldering of one end of the coilthereto or by other suitable connector 36. The coil means 35 is suitablyinsulated by conventional techniques. A retaining washer 38 isinterfitted in the insulation and firmly holds the coil 35 in the fixedposition shown, said retaining ring 38 being electrically connected tothe coil by the other end of the winding or by suitable connector 37.

It is to be expressly noted that coil 35 may be replaced by a suitabletoroidal shaped permanent magnet 35 having opposite poles on theinterior and exterior surfaces. When a permanent magnet is substituted,the electrical connection bypasses the magnet and is directly shuntedfrom bolt 32 to electrode 40. The electrical circuitry is then as shownin Fig. 7 of the drawings.

The fixed contact assembly of the interrupter device comprises anannular washer 39 afiixed to retaining washer 38 and a generallytoroidal shaped contact ring 40 which is brazingly mounted on the washer39 all of which are coaxially aligned with bolt 32. It is to be notedthat the electrical connection of the mounting bolt 32 to the fixedcontact 40 is through the coil 35 which thus places a magnetic influenceon the contact as shall be later explained. 1 g

The movable contact assembly comprises an elongated generallycylindrical plunger rod 41 having an enlarged head portion 42. Theplunger 41 is fixed to contact spring 31 through a suitable aperture inthe end wall 30' of the bellows, the connection being by brazing or thelike to seal the end wall 30 and cause the end wall, the contact spring31 and plunger to move as a unit. An annular flat movable contact plate43 is disposed in opposed relationship to the contact ring '40 and isbiased thereagainst by spring 44 which serves to maintain a constantcontact pressurebetween contacts 43 and 40. The spring 44' also servesas a lost motion connection to bias the Contact 43 for movement with theenlarged head 42 of plunger member 41. An anchor plate 45 is fixedlymounted by interfitting in the insulation of the housing 28 and servesas a fixed base plate for the other end of the contact and loss motion.biasing spring 44. Copper shunt strips 47 are disposed around spring 44to provide a convenient current bypass from contact '43 to plate 45, thecircuit continuing through the bellows 29 to contact spring 31. Theentire enclosure of housing 28 including bellows 29 is preferably sealedand an arc extinguishing fluid is disposed therein. Examples of arcextinguishing fluids are oil, carbon dioxide, dry air, sulfurhexafluoride, etc.

Contact 43 is biased away from contact 40' by a main biasing spring 46which engages the end surface 30 of g the bellows 29 and the other sideof plate 45. Spring 46' is considerably stronger than spring 44overpowering the latter to afford separation of the contacts- 13 401 Aguide member 48 may be centrally located on" plate 45 to provide abearing for the movable plunger 41.

Latch means 49 is provided to hold the contacts 4340 in engagementagainst the bias of spring 46. The latch means comprises a pair of hooklike members 50 which are pivotally mounted on suitable projection onthe outer portion of housing 28 at 51. A transverse slide memberinterconnector 52 is fixedly mounted by brazing or the like to each ofthe hook like members 50 at the upper surface thereof so that the twomembers 5%) act as a unitary latch as best shown in Figs. 1 and 3 of thedrawings.

The tripping means 55 for the latch means comprises a pair of spacedintegral arms 54a formed in or attached to the door 11. Each of the armsis formed with an elongated slot or aperture 54. A captive cocking rod53 is held within the slots 54 of the tripping means 55 and isengageable with the end of the bellows 30. The rod 53 is so aligned withthe end surfaces of the slots 54 so as to compress the bellows andcoactingly receive the hook like members 50 which fit thereover to latchthe contacts in the position shown in Figs. 1 and 2 of thedrawings. Fortripping purposes, a cam surface 56 is formed on the upper surface ofarms 54a to engage transverse member 51 to releasably raise the hookmembers 50. The relative length of the slots 54 and position of camsurface 56 is such that it allows a partial opening movement of the doorprior to transverse interconnecting rod 51 engaging with cam. surface 56to cause upward movement of the hook like members 50. Relatching upwardmovement of hook like members '50 with the captive rod 53 occurs by thecam surface formed in the leading edge 50a of the hook like members 50engaging with the rod member 53 as the door is moved inwardly (to the.left) when the rod 5 3 is against the right hand end of the slot asviewed in Fig. 1.

0peration.Assurne that the parts are in the position shown in Fig. l.The pull ring on the door is engaged manually by a hook stick or othersuitable device to pull the door outwardly or to the right as shown inFig. 3 of the drawings. As the door is moved outwardly, fuse cap 20parts with contact means 13, but spring contact means 31 of the loadinterrupter remains in electrical engage ment with the cap 20. The latchtripping arms 54a moving with the door causes upper cam surface 56thereon to engage the transverse rider bar 51 moving the latter upwardlyso as to cause hook members 50 to disengage from captive rod 53releasing the bellows end wall 30 for outwardly movement under the biasof spring 46. Assuming that conductor '57 (shown in schematic Figures 5and 6) is connected to a source of electrical energy, the normal currentpath through the fuse cutout when it is closed is along conductor 59through contact 13, through the fuse link, through the conductor 59a tothe other side of the line 58. During the interrupting cycle abovedescribed the current bypasses conductor 59 taking the alternate paththrough conductor 60, through the coil 35, through conductor 61 to fixedcontact 40, arcs the gap between contacts 40 and 43, follows through thebellows 29 through conductor spring 31 to the fuse cap 20 throughconductor 59a, to return conductor 58. The current in the annular coilmeans'35 sets up a magnetic field 62 which causes the. are 63 to move inthe direction shown by the arrows 64 causing a rapid movement of the arealong the periphery of the two contacts as shown semidiagrammatically inFig. 6. Rapid movement of the are 63 is such that deleterious pitting ofthe contacts does not occur. The arc, under the influence of themagnetic field, is thus forced into intimate contact with the unionizedare extinguishing fluid in the housing 28.

It will be apparent that a very short movement of the contacts isrequired in order to produce an. arc and the arc is rapidly extinguishedunder the dual influence of the rapid movement thereof as well as by thearc extinguishing fluid which is forced into contact of the arc'by themovement of the arc itself.

The door 11' continues its opening movement to the right causingdisengagement of the contact spring 3.],

r and the head of the fuse tube to completely interrupt the circuit. Thedoor and fuse tube may thus be removed from the cutout housing '10 instandard fashion.

When the door 11 is replaced, the door is rocked back into position, thefuse tube head 20 re-engaging the contact spring 31, the cocking bar 53re-engaging the end of the bellows compressing the latter against spring46 until latch hook 50 drops over cocking bar 53 to retain theloadinterrupter in latched cocked relation.

Although a specific embodiment has been shown and described, it is withfull awareness that many modifications thereof are possible. Theinvention, therefore, is not to be restricted except insofar as isnecessitated by the prior art and by the spirit of the appended claims.

What is claimed as the invention is:

l. A fuse cutout comprising first and second spaced terminal means,movable fuse means for electrically bridging said first and secondterminal means and load interrupter means electrically connected to saidfuse means and first terminal means, said load interrupter meanscomprising enclosure means, magnetic means within said enclosure means,first annular contact means disposed within said enclosure means andassociated with said magnetic means, and movable contact meanselectrically and operatively connected to said fuse means and normallydisposed in engaged movable relation to said first contact means withinsaid enclosure means so that disengaging movement of said fuse meansfrom said first terminal means affords movement of said movable contactmeans to spaced relation with said first contact means to interrupt theelectric circuit therebetween within said enclosure means.

2. A short movement load interrupting device comprising sealed enclosuremeans having a movable end portion and containing arc extinguishingfluid, annular coil means disposed Within said enclosure means, fixedannular first contact means magnetically associated and adjacent saidcoil means and electrically connected thereto, movable contact meansengaging said fixed contact means and operatively connected for movementwith said movable end portion of said sealed enclosure means, and meansbiasing said movable end portion outwardly to afford separating movementof said fixed and movable contact means, said separating movement of thecontacts affording an are which is rapidly spun by the magneticinfluence of said coil means for extinguishment by said areextinguishing fluid so that a relatively short separating movement ofthe contacts will interrupt relatively large electrical currents.

3. A fuse cutout comprising an insulated housing having movable closuremeans, first and second spaced terminal means fixedly disposed withinsaid housing, fuse means disposed on said closure means for detachablyelectrically bridging said first and second terminal means, and loadinterrupter means fixedly disposed within said housing and electricallyconnected to said fuse means and first terminal means for bypassing thecurrent therethrough upon movement of said closure means, said loadinterrupter means comprising sealed enclosure means, coil means withinsaid enclosure means electrically con nected to said first terminalmeans, first annular contact means disposed within said enclosure meansand electrically connected to said coil means, and movable contact meanselectrically connected to said fuse means and disposed for coactingassociation with said first contact means Within said enclosure means,said movable contact means being operatively connected to said closuremeans so that opening movement thereof affords move ment of said movablecontact means to spaced relation with said first contact means tointerrupt the electric circuit therebctween within said sealed enclosuremeans.

4. A short movement load interrupting device comprising sealed generallycylindrical enclosure means having a flexible entensible bellows forminga movable end portion and containing arc extinguishing fluid, annularcoil means coaxially disposed within said enclosure means, fixed annularfirst contact means coaxially disposed adjacent and within the magneticinfluence of said coil means and electrically connected thereto,relatively flat movable contact means coaxially aligned with andengaging said fixed contact means and operatively connected for movementwith said movable end portion of said sealed enclosure means, and meansbiasing said movable end portion outwardly to afford separating movementof said fixed and movable contact means, said separating movement of thecontacts affording an are which is rapidly spun around the periphery ofsaid contacts by the magnetic influence of said coil means forextinguishment by said are extinguishing fluid so that a relativelyshort separating movement of the contacts will interrupt relativelylarge electrical currents.

5. A cutout comprising spaced first and second terminal means, movablefuse means for electrically bridging said first and second terminalmeans, load interrupting means fixed relative to said terminal means andelectrically connected at one side to said first terminal means and onthe other side to said fuse means, said load interrupting meanscomprising sealed enclosure means having a movable end portion andcontaining arc extinguishing fluid, annular coil means disposed withinsaid enclosure means, fixed annular first contact mean adjacent andwithin the magnetic influence of said coil means and electricallyconnected thereto, movable contact means engaging said fixed contactmeans and operatively connected for movement with said movable endportion of said sealed enclosure means, and means biasing said movableend portion outwardly to afford separating move ment of said fixed andmovable contact means, said separating movement of the contactsaffording an arc which is rapidly spun by the magnetic influence of saidcoil means for extinguishment by said are extinguishing fluid so that arelatively short contact movement will interrupt relatively largecurrents.

6. A fuse cutout comprising an insulated housing, door means rotatablymounted for closing said housing, first and second spaced terminal meansdisposed within said housing, fuse means fixed on said door means forelectrically bridging said first and second terminal means, and loadinterrupter means fixed within said housing and detachably electricallyconnected to said fuse means, said load interrupter means comprisingsealed enclosure means, coil means within said enclosure meanselectrically connected to said first terminal means, first annularcontact means disposed within said enclosure means and electricallyconnected to said coil means, and movable contact means for cooperationwith said first contact means and electrically and operatively connectedto said fuse means, means biasing said movable contact means away fromsaid first contact means, latch means operatively associated with saidmovable contact means to maintain the latter in engagement with saidfirst contact means against said biasing means, latch tripping meansfixed to said door means and operable to release said latch means sothat opening movement of said door means affords tripping movement ofsaid latch means to in turn alford movement of said movable contactmeans to interrupt the circuit therebetween within said sealed enclosuremeans and thereby prevent arcing between said fuse means and said firstterminal means.

7. A short movement load interrupting device comprising sealed enclosuremeans having a movable end portion and containing arc extinguishingfluid, magnetic field means disposed within said enclosure means, fixedannular first contact means adjacent and under the influence of saidmagnetic means, movable contact means engaging said fixed contact meansand operatively connected for movement with said movable end portion ofsaid sealed enclosure means, and means biasing said movable end portionoutwardly to afford separating movement of said fixed and movablecontact means, said sepa- 7 rating movement of the contacts aifording anarc which is rapidly spun by the magnetic influence of said magneticmeans for extinguishment by said arc extinguishing fluid so that arelatively short contact movement will interrupt relatively largecurrents.

8. A fuse cutout comprising first and second spaced terminal means,movable fuse means electrically bridging said first and second terminalmeans, and load interrupting means electrically connected to said fusemeans and said first terminal means, said load interrupting meanscomprising sealed enclosure means containing an arc extinguishing fluid,magnetic means disposed within said enclosure means, stationary contactmeans disposed within said enclosure means and magnetically associatedWith said magnetic means, and movable contact means disposed Within saidenclosure means and electrically and operatively connected to said fusemeans, said movable contact means normally disposed in engaged movablerelation to said stationary contact means and operative to be disengagedfrom said stationary contactmeans upon disengaging movement of said fusemeans from said first terminal means so that an arc is drawn betweensaid contact means, said stationary contact means and said movablecontact means having a substantial dimension generally normal to thedirection of said disengaging movement of said movable contact and saidmagnetic means acting on said are and resulting in movement of said arcon said contact means and through said are extinguishing fluid, wherebyrelatively short separation of said contact means interrupts relativelylarge currents.

9. A short movement load interrupting device com- 8 prising sealedenclosure means having a movable end portion and containing an arcextinguishing fluid, magnetic means disposed within said enclosuremeans, stationa'ry contact means, disposed Within said enclosure meansand adjacent said magnetic means, movable contact means disposed Withinsaid enclosure means in engageme'nt With said stationary contact andoperatively connected for movement With said movable end portion of saidsealed enclosure means, and means biasing said movable end portionoutwardly to afford separating movement of said stationary and movablecontact means, said stationary and movable contact means having asubsta'n tial dimension generally normal to the direction of saidseparating movement, said magnetic means acting upon the are drawnbetvveen said contact means on separation thereof and aflording movementof said are on said contact means and through said arc extinguishingfluid, whereby relatively short separation of said contact meansinterrupts relatively large currents.

References Cited in the file of this patent UNITED STATES PATENTS659,671 Hewlett Oct. 16, 1900 2,065,802 Graves Dec. 29, 1936 2,411,893Peters Dec. 3, 1946 2,734,966 Schneider Feb. 14, 1956 2,824,190 MikosFeb. 18, 1958 FOREIGN PATENTS 736,870 France Sept. 26, 1932

